Question

помогите )))И обьясните

Answer 1

$sqrt{25a} + sqrt{16a} - sqrt{64a}= sqrt{5 ^{2}*a } + sqrt{4 ^{2}*a } - sqrt{8 ^{2}*a }=$$sqrt{5^{2}} sqrt{a} +sqrt{4^{2}} sqrt{a} - sqrt{8^{2}} sqrt{a} = 5 sqrt{a} +4sqrt{a} - 8sqrt{a} =9 sqrt{a} -8 sqrt{a} = sqrt{a}$